Mexican sunflowers yield dozens of showy daisy-like blooms with petals in fiery colors of red, orange, or yellow, all with yellow centers. The serrated ovate leaves are dark green on tall, sturdy stems. Plant seeds or seedlings in the spring to enjoy an ongoing display of profuse blooms throughout the summer into fall. These annuals are a welcome addition to the butterfly garden thanks to their nectar-rich shallow blossoms that meet a pollinator’s needs. Unlike many butterfly-friendly plants that are small in stature, the tall blooms of the Mexican sunflower bring butterflies right up to eye level, making them easier to observe. A mature stand of sunflowers makes a good addition to the vegetable garden, as the pollinators they attract will help increase your vegetable yields. One packet of Mexican sunflowers will give you many vasefuls of cut flowers throughout the summer. Plant them with companions that thrive in the same sunny site and average soil, like cosmos and zinnias, which will also act as cut-and-come-again blooms for the cutting garden.
Light
Full sun is a critical factor in growing healthy Mexican sunflowers. Plants growing in shady areas may not bloom, will flop over, and might suffer from fungal diseases.
Soil
Save your soil amendments for fussier flowers like roses and dahlias, because Mexican sunflowers like lean soils with low nutrient content. Good drainage is important to prevent problems like root rot. Sandy or rocky soils more closely resemble the native soils of Mexico where the plants grow wild.
Water
Mexican sunflowers are drought tolerant throughout their life cycle and don’t need watering, contributing to their low-maintenance charm. Wet soil is not tolerated by Mexican sunflowers, but if your area gets more rain than average, you can compensate for this by planting them in soil with excellent drainage.
Temperature and Humidity
Mexican sunflowers love hot weather, even days with triple-digit temperatures. Conversely, cool weather stops the Mexican sunflower in its tracks. When nighttime temperatures are in the 60s, it’s the right time to grow Mexican sunflowers. Average humidity is best for healthy plants. Provide extra spacing for plants in humid areas to prevent powdery mildew.
Fertilizer
Mexican sunflowers grow just fine without any supplemental fertilizer. In areas with especially depleted soils, you can add an all-purpose flower fertilizer at the beginning of the season to get plants off to a quick start. For the amount, follow the product label instructions.
Types of Mexican Sunflowers
‘Torch’ is the mainstay of Mexican sunflowers, growing in gardens since the 1950s.‘Fiesta del Sol’ is a dwarf variety for smaller gardens or containers, growing between 2 and 3 feet in height. ‘Goldfinger’ is another good dwarf variety.
Pruning
Pruning Mexican sunflowers isn’t necessary but can help to get lanky plants under control or to keep overgrown plants in bounds. Keep in mind that you may sacrifice some blooms when pruning. Cut off the top 1/3 of the plant when it’s experiencing a lull in blooming to both deadhead and tidy the plant.
Propagating Mexican Sunflowers
Although the Mexican sunflower is easy to grow from seed, if you can’t find your favorite variety you can also propagate plants by stem cuttings. Unlike established Mexican sunflowers, this type of propagation requires daily watering to get the cuttings to root. Here’s how it’s done:
How to Grow Mexican Sunflowers From Seed
The small, triangular seeds of Mexican sunflower germinate easily in warm, moist soil. The quickest approach is to sow the seeds outdoors, at the same time you plant tomatoes, two weeks after the last frost. In short summer areas, zone 4 and colder, start the seeds indoors six weeks before the last frost to ensure the plants have time to mature and bloom before fall. Because of its large size and rapid growth, plant no more than a few Mexican sunflower seeds in a container. Sow seeds directly in the pot, as large plants are difficult to transplant. Use a soilless potting mix with good drainage.
Potting and Repotting Mexican Sunflowers
You can also grow dwarf varieties of Mexican sunflowers in pots on your patio, deck, or balcony. Like for all patio plants, breathable clay or terra cotta pots with large drain holes are the best choice because they keep the soil cooler than plastic pots and ensure evaporation. Because Mexican sunflowers are annuals in most zones, choose a pot that will fit the mature plant without requiring any repotting during their single-season lifespan. A gallon-pot is a good size for one sunflower. Plant it in the center of the pot. Mexican sunflowers are also attractive in larger planters with trailing plants like million bells or portulaca, which also appreciate full sun and dry conditions.
Overwintering
Mexican sunflower doesn’t survive the winter outside of its native range. Count on starting new plants in the spring.
Common Pests and Plant Diseases
Snails and slugs sometimes bother Mexican sunflowers, especially in rainy weather. Place a piece of damp cardboard beside plants and collect the pests when they hide during daylight hours. The plants might suffer from fungal diseases if the area is too shady, and they might suffer from powdery mildew if they are too crowded, especially in humid areas.
How to Get Mexican Sunflowers to Bloom
Unlike other plants, Mexican sunflowers thrive in rocky or sandy soil. In fact, you might get better blooms from poor soil than you will from robust, nutrient-rich soil. Sun is also a factor, as these plants need a lot of it. If they still aren’t blooming, consider that they might have too much water sitting around the roots; the soil must be well-draining.
